P2574: Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Low

What it means

The DOR deterioration sensor signal voltage reads below the lower limit — short to ground or internal short.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The DOR catalyst deterioration sensor sends a signal to the engine control module about the catalyst system. P2574 sets when that signal falls below the circuit's allowed lower limit, which can happen if the signal is pulled to ground or the sensor has an internal fault.

Common causes

Most likely first.

1. Signal wire shorted to ground
2. Connector pins corroded - high contact resistance
3. Harness chafing through insulation

Symptoms

• Check engine light

How to diagnose it

1. Check freeze-frame data and live sensor data to confirm the DOR deterioration signal is low when the fault is present.
2. Inspect the sensor connector and harness for chafing, corrosion, or a signal wire contacting ground.
3. Check the sensor reference and return connections, since a poor connection can affect the low signal reading.
4. Test the signal wire for a short to ground and check circuit continuity against the manufacturer's specifications.
5. If the wiring and connector pass, test the DOR deterioration sensor for an internal short before checking the module input.

Common fixes

• Repair signal-wire insulation where it is shorted to ground.
• Clean or repair corroded sensor connector terminals.
• Secure and reroute chafed wiring away from grounded surfaces.
• Replace the DOR deterioration sensor if it has an internal short.

Can I keep driving?

The listed symptom is a check-engine light, and no limp mode is indicated, so driving is generally possible if the vehicle runs normally. The DOR catalyst monitor may not be able to assess the system until the low signal is repaired.